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Biomedical subjects

E White

Publications and source records attributed to E White.

At least 325 records · Page 18Linked to original sources
PubMed1986

Biomaterial aspects of Interpore-200 porous hydroxyapatite.

Interpore-200 is the product of over 11 years of continuous research and development. It has been investigated at over 25 research centers in a wide variety of animal and human implant settings, including alveolar ridge augmentation, periodontics, and orthognathic reconstructions. The biomaterial aspects of Interpore-200 show the following: Interpore-200 has a highly interconnected, three-dimensional porosity that is uniform and consistent. The hydroxyapatite manufactured from marine corals is biocompatible and nontoxic. Interpore-200 is essentially pure hydroxyapatite, with the balance consisting of tricalcium phosphate. Interpore-200 is approximately 55 to 65 per cent porous with nominal pore diameters of 200 micron. Unlike nonporous materials, Interpore-200 is osteoconductive and results, when placed next to a viable bone, in an advancing front of bone into the implant. From 50 to 88 per cent of the porosity within the implant is filled with woven and lamellar bone within 3 months. Moreover, the surfaces of Interpore-200 are intimately bonded with the bone tissue. The biomechanical properties of Interpore-200 blocks are similar to those of a cancellous bone graft. Once ingrown with vascularized bone tissue, the defect site is, in effect, restored. Interpore-200 adequately matches the elastic properties of bone so that stresses necessary to maintain healthy bone are transmitted throughout the regenerated region. Extensive animal and clinical studies have shown that nonporous implants or implants without interconnected porosity can result in aberrant mineralization, stress shielding, low fatigue strength, and bulk displacement. Hydroxyapatite with interconnected porosity like Interpore-200 reacts differently than materials with limited or no porosity. In animals, Interpore-200 exhibits 0 to 5 per cent biodegradation per year. Moreover, this minimal biodegradation is compensated by regeneration of bone. These studies have now been extended for 4 years. Interpore-200 and its ingrown bone are remodeled in response to the same chemical and biomechanical forces that remodel normal bone. Therefore, Interpore-200 responds in accordance to Wolff's law. Having achieved an optimal combination of biomaterial (hydroxyapatite) in an ideal porous structure (replamineform), Interpore-200 fulfills the expectation of early researchers in the basic sciences who demonstrated that an interconnected porous material is better tolerated by the body than the same material in solid form.(ABSTRACT TRUNCATED AT 400 WORDS)

Alveolar Ridge Augmentation↗
PubMed1986

Chronic fetal stress and the risk of infant respiratory distress syndrome.

The relationship between five conditions of chronic fetal stress and the incidence of infant respiratory distress syndrome (RDS) was investigated among 614 premature (less than or equal to 36 weeks) infants delivered at the University of Washington Hospital from 1977 to 1980. The strongest association found was a protective effect of abnormal antepartum testing (nonreactive nonstress test, positive contraction stress test, or low or falling maternal urinary estriols). Among the 45 infants with abnormal antepartum testing, the probability of RDS was 15.0 versus 33.8% for the infants without the complication (odds ratio = 0.35, P less than or equal to .01, adjusted for gestational age and mode of delivery). Rupture of the membranes for greater than 24 hours (N = 151), amnionitis (N = 63), and vaginal bleeding beginning more than 24 hours before delivery (N = 108) were each associated with a reduced risk of RDS (adjusted odds ratios = 0.63, 0.51, and 0.58, respectively, P less than or equal to .05). Hypertensive disease of pregnancy was not associated with a decreased risk of RDS; in fact, the opposite trend occurred (N = 96, odds ratio = 1.67, P = .07). The associations with RDS were not explained by differences between births with and without each complication in terms of gestational age, mode of delivery, absence of labor, administration of antenatal steroids, and other complications of pregnancy. This study adds support to the hypothesis that certain conditions associated with chronic fetal stress lead to an acceleration in pulmonary maturity.

Chronic Disease↗
PubMed1986

Maternal smoking and infant respiratory distress syndrome.

The relationship between maternal smoking and infant respiratory distress syndrome (RDS) was investigated among 550 premature (36 weeks or less) births delivered at the University of Washington Hospital from 1977 to 1980. Forty-five percent of the mothers were smokers. To avoid bias due to the reduced birth weight of infants of smokers, infants of smokers and nonsmokers were compared within small gestational age categories (two-week intervals) and not by birth weight categories. Infants of mothers who smoked had a reduced incidence of RDS for their gestation compared with infants of nonsmokers. The probability of RDS (adjusted for gestational age and method of delivery) was 25% for the infants of smokers versus 38% for the infants of nonsmokers (odds ratio = 0.55, P = .005), equivalent to approximately a 1.5-week acceleration in lung maturity for infants of smokers. The smoking effect was not explained by demographic differences between smokers and nonsmokers, nor by differences in the incidence of pregnancy complications between the two groups. This study adds support to the theory that adverse pregnancy conditions may lead to an acceleration in pulmonary maturity to allow earlier extrauterine adaptation.

Female↗
PubMed1985

An investigation of the relationship between cesarean section birth and respiratory distress syndrome of the newborn.

To clarify the nature of the association between respiratory distress syndrome and Cesarean section birth, a study was conducted which compared 273 premature (36 weeks or less) Cesarean-delivered infants with 341 premature vaginally delivered infants who were born at the University of Washington Hospital from January 1, 1977 through March 31, 1980. The gestational age-adjusted probability of respiratory distress syndrome was higher among the Cesarean cohort compared with the vaginal cohort (38.2% vs. 27.6%, odds ratio = 1.63, 95% confidence interval = 1.11-2.39). Three alternative explanations for the association of Cesarean section with respiratory distress syndrome other than causation were tested, and each was rejected. The association was not explained by 1) improper timing of elective Cesarean deliveries; 2) misclassification of cases of mild, transient respiratory distress (which may be more common after Cesarean birth) as respiratory distress syndrome; or 3) the differences in the occurrence of pregnancy complications preceding Cesarean births compared with vaginal births. Lack of labor appears to account for part of the increased risk of respiratory distress syndrome among infants delivered by Cesarean section. The gestational age-adjusted probabilities of respiratory distress syndrome were 47.0% for Cesarean birth without labor, 35.4% for Cesarean birth preceded by labor, and 27.6% for vaginal birth.

Birth Weight↗
PubMed1985

Percutaneous extraction of renal stones: experience in 100 patients.

Recent developments in technology and instrumentation have made it possible to remove most kidney stones and many ureteral stones percutaneously. The first 100 cases at this institution were reviewed in which grasping, ultrasonic lithotripsy, basketing, and irrigation were used. In all cases, the follow-up was at least 1 year. The success rates were 92.4% for renal pelvic stones, 92% for caliceal stones, and 68% for ureteral stones. Ten of the 14 patients who required open operation after an unsuccessful percutaneous procedure were among the first 18 patients, whereas only one open operation was needed in the last 40 patients. Proper patient selection; the size, number, and location of stones; proper selection of the nephrostomy site; and the expertise of the operator are critical factors in determining the success rate. To date, the short-term results of percutaneous stone removal have been as good as those of open surgery.

Adolescent↗
PubMed1984

Independent mutations in Ad2ts111 cause degradation of cellular DNA and defective viral DNA replication.

An adenovirus mutant, Ad2ts111, has previously been shown to be temperature sensitive for viral DNA replication in vivo and also to induce degradation of cellular DNA. Soluble nuclear extracts prepared from Ad2ts111-infected HeLa cells grown at either the permissive (32 degrees C) or the nonpermissive (39.5 degrees C) temperature are thermolabile for elongation but not for initiation of DNA replication in vitro. Adenovirus single-stranded-DNA-binding protein purified from wild-type-infected cells can complement these extracts at the restrictive temperature in vitro. The DNA-binding protein synthesized in Ad2ts111-infected cells is stable at the nonpermissive temperature and is phosphorylated, as is the wild-type protein. In contrast, the mutant DNA-binding protein synthesized in Ad5ts125-infected cells is unstable. Ad2ts111 and Ad5ts125 do not complement each other for virus growth in vivo. These results suggest that Ad2ts111 contains a mutation in the DNA-binding protein that affects viral DNA synthesis. Finally, we demonstrated that, unlike viral DNA synthesis, the induction of cellular DNA degradation in Ad2ts111-infected cells is not temperature sensitive and that this phenotype is a result of a mutation in early region 1 on the virus genome. Thus, the two phenotypes displayed in Ad2ts111-infected cells, namely, the temperature-sensitive replication of viral DNA and the degradation of cell DNA, are the result of two separate mutations.

Adenoviruses, Human↗
PubMed1984

Mutations in the gene encoding the adenovirus early region 1B 19,000-molecular-weight tumor antigen cause the degradation of chromosomal DNA.

The adenovirus mutant Ad2ts111 has been previously shown to contain a mutation in the early region 2A gene encoding the single-stranded-DNA-binding protein that results in thermolabile replication of virus DNA and a mutation in early region 1 that causes degradation of intracellular DNA. A recombinant virus, Ad2cyt106, has been constructed which contains the Ad2ts111 early region 1 mutation and the wild-type early region 2A gene from adenovirus 5. This virus, like its parent Ad2ts111, has two temperature-independent phenotypes; first, it has the ability to cause an enhanced and unusual cytopathic effect on the host cell (cytocidal [cyt] phenotype) and second, it induces degradation of cell DNA (DNA degradation [deg] phenotype). The mutation responsible for these phenotypes is a single point mutation in the gene encoding the adenovirus early region 1B (E1B) 19,000-molecular-weight (19K) tumor antigen. This mutation causes a change from a serine to an asparagine in the 20th amino acid from the amino terminus of the protein. Three other mutants that affect the E1B 19K protein function have been examined. The mutants Ad2lp5 and Ad5dl337 have both the cytocidal and DNA degradation phenotypes (cyt deg), whereas Ad2lp3 has only the cytocidal phenotype and does not induce degradation of cell DNA (cyt deg+). Thus, the DNA degradation is not caused by the altered cell morphology. Furthermore, the mutant Ad5dl337 does not make any detectable E1B 19K protein product, suggesting that the absence of E1B 19K protein function is responsible for the mutant phenotypes. A fully functional E1B 19K protein is not absolutely required for lytic growth of adenovirus 2 in HeLa cells, and its involvement in transformation of nonpermissive cells to morphological variants is discussed.

Antigens, Neoplasm↗
PubMed1984

Nuclear envelope localization of an adenovirus tumor antigen maintains the integrity of cellular DNA.

The adenovirus early-region 1B 19,000-molecular-weight tumor antigen is required for oncogenic transformation of cells by adenovirus. We have demonstrated that this tumor antigen is located in the nuclear envelope of infected and transformed cells and that a fraction of the protein within the nuclear envelope is associated with the nuclear lamina. During cell division in the transformed cells, the nuclear envelope containing the tumor antigen dissociates at metaphase and then reforms around the separated daughter chromosomes at telophase. Adenovirus mutants carrying lesions in the gene encoding this tumor antigen cause degradation of host cell chromosomal DNA, and in these mutants, the intracellular localization of the 19,000-dalton protein is altered. These results demonstrate that components of the nuclear envelope function in the organization of chromatin in infected and transformed cells and that a virus-encoded protein plays a critical role in this process.

Adenoviridae↗
PubMed1983

Polyamines in Trichomonas vaginalis.

Trichomonas vaginalis was grown in a modified Bushby's medium and putrescine, spermidine and spermine levels were determined in extracts from 24- and 48-h cultures and also in the culture media. All three polyamines were present in T. vaginalis extracts; the putrescine level and putrescine/spermidine ratio were much higher than those reported for other protozoa or for mammalian tissues. There were no significant differences between 24-h and 48-h amine levels per mg protein in these extracts, but amine levels per cell were higher at 24 than at 48 h. The spent culture media had a much higher putrescine content than corresponding uninoculated media and it was concluded that T. vaginalis secreted putrescine into the culture medium.

Animals↗
PubMed1983

Identification of tubulin in Dictyostelium discoideum: characterization of some unique properties.

We used three antitubulin antibodies to localize Dictyostelium tubulin subunits on two-dimensional polyacrylamide gels by Western blotting. All three antibodies, a polyclonal antibody against sea urchin alpha- and beta-tubulin and two monoclonal antibodies against yeast alpha-tubulin, recognize the same set of polypeptides with a molecular weight of 55,000 while focusing at a pH far more basic than all other tubulins. Each antibody specifically stains the microtubule system of slime mold amoebae by indirect immunofluorescence. The microtubule system can be isolated as a major component of the amoeba cytoskeleton, and these preparations are greatly enriched for the presumptive tubulin subunits. The microtubules of these cytoskeletons are resistant to being depolymerized by millimolar concentrations of calcium, while they retain their cold sensitivity. Comparison of peptide maps of slime mold and brain alpha-tubulins indicates that the proteins are related but not identical. Possible explanations for these unusual characteristics are discussed.

Calcium↗
PubMed1983

Amine content of vaginal fluid from patients with trichomoniasis and gardnerella associated non-specific vaginitis.

Amounts of putrescine, cadaverine, and tyramine were measured in vaginal washings from five patients with non-specific vaginitis (NSV) associated with Gardnerella vaginalis, five patients with trichomoniasis, and five healthy controls. Putrescine and cadaverine were present in all but one sample from the infected patients; tyramine was found in four of five samples from the women with NSV and in two of five samples from those with trichomoniasis. The mean cadaverine to putrescine ratio was significantly higher in the patients with NSV than in those with trichomoniasis. Samples from the five controls contained only very small amounts of any of the three amines. The amine content of nine of 10 samples from the infected women was reduced to normal values after metronidazole treatment. The possible sources of the amines from Trichomonas vaginalis and Gardnerella vaginalis are discussed with reference to the clinical response to treatment.

Amines↗
PubMed1983

Intraocular response to cotton, collagen and cellulose in the rabbit.

Cotton, cellulose and collagen were each implanted into the anterior chamber and anterior vitreous of rabbit eyes. The ocular inflammatory response was studied clinically over a 28-day period and histologically at seven and 28 days. In general, cotton was the least reactive, with collagen and cellulose moderately reactive. Cellulose was associated with progressive inflammation and marked granulomatous response. Vitreous implants showed minimal inflammation, with virtually no response to cotton. These findings support current literature suggesting that the use of cellulose in ophthalmic surgery may increase the risk of postoperative granulomatous inflammation.

Animals↗
PubMed1982

Near-drowning complicated by brain abscess due to Petriellidium boydii.

Extracutaneous infection from Petriellidium boydii is an unusual occurrence despite the ubiquity of the organism in nature. Central nervous system infection by this organism is extremely rare, only seven previous reports having been found. The rarity of this manifestation prompted the report of a brain abscess occurring in a previously healthy youth after a near-drowning. The source of the infection was likely to have been the river water at the accident site, from which P boydii was isolated. Although previous in vitro susceptibility data and failure of amphotericin B therapy in a similar infection suggested miconazole treatment might be beneficial, the organism causing the brain abscess was resistant to miconazole and amphotericin B. This report emphasizes the urgent need for safer and more predictably effective alternatives to currently available antifungal agents.

Adult↗